CT system for security check and method thereof

1. A method in a Computed Tomography (CT) system for security check, comprising steps of:

reading inspection data of an inspected object;

inserting at least one previously collected three-dimensional (3D) Fictional Threat Image (FTI) into a 3D inspection image of the inspected object, wherein the 3D inspection image is obtained from the inspection data, and wherein even if the 3D FTI is blocked by a part of the inspected object at a certain angle of view, the 3D FTI can be observed by adjusting the 3D inspection image including 3D FTI to another angle of view;

receiving a selection of at least one region in the 3D inspection image including the 3D FTI or at least one region in a two-dimensional (2D) inspection image including a 2D FTI corresponding to the 3D FTI, wherein the 2D inspection image is obtained from the 3D inspection image or is obtained from the inspection data; and

providing a feedback of the 3D inspection image including at least one 3D FTI in response to the selection.

2. The method according to claim 1 , wherein the step of receiving a selection of at least one region in the 3D inspection image including the 3D FTI or at least one region in a 2D inspection image including a 2D FTI corresponding to the 3D FTI comprises:

receiving coordinate positions of a part of the 3D inspection image or the 2D inspection image associated with the selection.

3. The method according to claim 1 , wherein the step of providing a feedback of the 3D inspection image including at least one 3D FTI in response to the selection comprises at least one of:

judging whether the at least one selected region includes the at least one 3D FTI;

popping up a dialog to confirm that the 3D inspection image includes at least one 3D FTI;

providing text indication on an interface to confirm that the 3D inspection image includes at least one 3D FTI;

highlighting the part of the 3D inspection image or the 2D inspection image associated with the selection;

marking the part of the 3D inspection image or the 2D inspection image associated with the selection; and

filling the part of the 3D inspection image or the 2D inspection image associated with the selection with a particular color or pattern.

4. The method according to claim 1 , wherein at least one spatial characteristic parameter of the inspected object is calculated according to the inspection data, and at least one 3D FTI is inserted into the 3D inspection image of the inspected object based on the spatial characteristic parameter.

5. The method according to claim 4 , wherein the spatial characteristic parameter is related to at least one of position, size and orientation of the 3D FTI to be inserted.

6. The method according to claim 1 , wherein selection of at least one region comprises selection of a part of the displayed 3D inspection image at an angle of view.

7. The method according to claim 6 , wherein in 3D rendering of the 3D inspection image, point cloud information characterizing the inspected object is recorded, and the step of providing a feedback of the 3D inspection image including at least one 3D FTI in response to the selection comprises:

obtaining a sequence of point cloud information clusters of different objects in the inspected object by division;

determining at least one selected region from the sequence of point cloud information clusters of the different objects based on a predetermined criterion; and

judging whether the at least one selected region includes the at least one 3D FTI.

8. The method according to claim 1 , wherein selection of at least one region comprises selection of a part of the displayed 3D inspection image at multiple angles of view.

9. The method according to claim 8 , wherein selection of at least one region comprises selection of a part of the displayed 3D inspection image at two different angles of view, wherein the two different angles of view are substantially orthogonal to each other, transparent regions are removed from the inspection data to obtain a hierarchical bounding box of opaque regions in the inspection data, and then a scene depth is rendered for the hierarchical bounding box to obtain a depth map on the front side and a depth map on the back side, and the step of providing a feedback of the 3D inspection image including at least one 3D FTI in response to the selection comprises:

performing retrieval in the depth map on the front side and the depth map on the back side respectively according to a region selected by a user at a first angle of view to generate a first bounding box;

performing ray casting with the generated first bounding box as a texture carrier;

performing retrieval in the depth map on the front side and the depth map on the back side respectively according to a region selected by the user at a second angle of view substantially orthogonal to the first angle of view, to generate a second bounding box;

performing a Boolean intersection operation on the first bounding box and the second bounding box in an image space, to obtain a marked region in a 3D space as at least one selected region; and

judging whether the at least one selected region includes the at least one 3D FTI.

10. The method according to claim 1 , wherein, the step of inserting at least one 3D FTI into a 3D inspection image of the inspected object comprises:

dividing the 3D inspection image to obtain multiple 3D sub-images of the inspected object;

calculating distances between and positions of the multiple 3D sub-images; and

inserting the 3D FTI based on the calculated distances and positions.

11. The method according to claim 1 , wherein the step of inserting at least one 3D FTI into a 3D inspection image of the inspected object comprises:

determining transparent parts and opaque parts in volume data of the inspected object based on opacity values of voxels;

determining positions and sizes of cases of the inspected object from the opaque parts of the volume data;

determining candidate insertion positions in transparent regions in the range of the cases; and

selecting at least one position from the candidate insertion positions according to a predetermined criterion to insert at least one 3D FTI into the at least one selected position.

12. The method according to claim 1 , wherein the step of inserting at least one 3D FTI into a 3D inspection image of the inspected object comprises:

removing a background image from the 2D inspection image, to obtain a 2D foreground image;

determining a 2D insertion position of a 2D FTI in the 2D foreground image;

determining a position of a 3D FTI in the 3D inspection image along a depth direction at the 2D insertion position; and

inserting at least one 3D FTI into the determined position.

13. The method according to claim 1 , further comprising: inserting a 2D FTI corresponding to the at least one 3D FTI into the 2D inspection image of the inspected object.

14. A Computed Tomography (CT) system for security check, comprising:

a CT scanning device configured to obtain inspection data of an inspected object;

a storage configured to store the inspection data;

a display device configured to display a three-dimensional (3D) inspection image and/or two-dimensional (2D) inspection image of the inspected object, wherein the 3D inspection image is obtained from the inspection data, and the 2D inspection image is obtained from the 3D inspection image or the inspection data and wherein even if the 3D FTI is blocked by a part of the inspected object at a certain angle of view, the 3D FTI can be observed by adjusting the 3D inspection image including 3D FTI to another angle of view;

a data processor configured to insert at least one previously collected 3D Fictional Threat Image (FTI) into the 3D inspection image of the inspected object; and

an input device configured to receive a selection of at least one region in the 3D inspection image including the 3D FTI or at least one region in the 2D inspection image including a 2D FTI corresponding to the 3D FTI, wherein the data processor is further configured to provide a feedback of the 3D inspection image including at least one 3D FTI in response to the selection.

15. The CT system for security check according to claim 14 , wherein the data processor is further configured to calculate at least one spatial characteristic parameter of the inspected object according to the inspection data, and insert at least one 3D FTI into the 3D inspection image of the inspected object based on the spatial characteristic parameter.

16. The CT system for security check according to claim 14 , wherein the spatial characteristic parameter is related to at least one of position, size and orientation of the 3D FTI to be inserted.